Because they are also very ‘dry’, i.e. have very low water content (typically less than 5% water), they are the best materials to add to wet food waste to balance things out and ensure there is enough heat to drive off excess water as steam.

By the way this use has nothing to do with aeration and very little to do with balancing carbon/nitrogen ratios!

(Please note – Ignore the advice on many cold composting sites that scrunched up newspaper and or cereal packet cardboard will provide aeration – in the HOTBIN they WILL NOT create aeration pockets – quite the reverse – the paper and card will be soaking wet within hours and form a matted impervious layer to airflow. It is highly likely the newspaper will come out when you empty the bin as a flattened blob of soggy newspaper.

It is essential you mix both the paper and the cardboard into the waste rather than just add it in as a layer on the top. When adding food waste ALWAYS also add bulking agent. The bulking agent will form a supportive structure (think building blocks) around which air can flow.

Why will paper and corrugated paper compost quickly but not newspaper?

It is easy to think all paper products come from wood so they should all decompose at the same rate.
We know that thin high surface area materials will decompose faster – so cardboard is faster than a wood branch piece as the bacteria have more surface area to attack. If we assume and example where surface area is the same and the temperature is the same, the speed at which wood products compost is directly related to the amount of lignin contained – so hard wood decompose slower than soft woods.

We can take this analogy a little further to explain newspaper and white office paper – the comparison is made in the table below.

Comparison table

Speed
(At 60C)

Material

Notes

Fast
(days)

White paper (e.g. office, A4 copier, coffee filters)

The caustic part of the Kraft paper pulping process removes lignin to leave only cellulose fibres.Shredded it rather than crunch it up. Sprinkle in little and often – thick layers will quickly get wet and form an impervious mush that prevents airflow.

Fast
(days)

Corrugated brown cardboard boxes, egg cartons

Although processed, about 5-10% lignin remains.Corrugated cardboard has the advantage of trapped air/air channels. Shredded or tear up – large sheet will block airflow

Medium (weeks)

Newsprint/papers
Cardboard sheets

This is low cost paper – the expensive lignin removal stage is not undertaken – it is small wood fibres. (Compare to white office paper above).Ensure shredded or scrunched up. It will compost far more slowly than food, grass and most other wastesDo not add whole cereal boxes – tear up and spread / mix into waste. Add sparingly – if attempting to dry wet waste, much better to use office paper or corrugated cardboard.

Everyone tends to have corrugated cardboard boxes, but tearing them up can be tiresome. You can quickly cut into strips using a craft or Stanley knife – but you need to take care and do this correctly to avoid taking your fingers of! A safer way is to see if your office shredder is a ‘multi sheet’ unit. If it is it will shred 8 sheets of paper at a time and you will find it will shred most cardboard boxes. See photo’s below. Please keep in mind if you put too much strain on a low sheet feeder it will just overheat and conk out!

A useful post on dealing with excess water in the HOTBIN can be found on our online FAQ : Excess Water Post

Yes you can compost it. BUT!!

Problems will arise if the heap does not get above 40C – the seeds will survive cold composting and you will spread the seeds when the compost is used. A hot compost heap (40-60C) will kill the seeds.

However as this is such an invasive and tough weed, you need to check that the seeds/bits are only added to the top of a already hot pile, that they stay near the top (do not fork in or turn the pile/HOTBIN as seeds will fall down to cooler base). Finally, after hot composting, give your compost a ‘germination test’ – By this we mean leave the compost in an open maturation pile for a few months to check to ensure the Horsetail does not re-sprout. If it does, gently tease out all roots and rhizomes again and zap it through the hot compost again.

This may sound painstaking – but so will your efforts to remove it from soil in the first place. Are there any other options? Passing the waste on to your local authority to handle is not a great option. The seeds and bits can drop and disperse on roads and neighbours plots. If you are unsure, perhaps this is one case where it is better to burn the weeds (subject to local authority rules of course!).

Horsetail or Mare’s Tail (Equisetum Arvense) is an invasive, deep-rooted perennial weed with fast-growing rhizomes (underground stems) that quickly send up dense stands of foliage that will spread quickly to form a dense carpet of foliage, crowding out less vigorous plants in beds and borders.

Horsetail is easily recognised by its upright, fir tree-like shoots that appear in summer. In spring, fertile light brown stems, 20-50cm (10-20in) tall, appear with a cone-like spore producing structure at the end of the stems. In summer, sterile green shoots develop into fir tree-like plants, 60cm (2ft) tall.

The creeping rhizomes of this pernicious plant may go down as deep as 2m (7ft) below the surface, making them hard to remove by digging out, especially if they invade a border. They often enter gardens by spreading underground from neighbouring properties or land.

What comes out of your compost heap, compost bin and indeed your HOTBIN can vary an awful lot.

With many HOTBIN® composters coming up to their first autumn, there will be a lot of hot compost being taken out and used in the garden. We thought it would be good idea to let you know what to expect as ‘looks can be deceptive’!

To do this we will look at several batches of compost alongside some HOTBIN composts. Suggest how they might be graded based on common expert visual assessments. Then we will take you on a journey beyond the first look to give you some insight into compost stability and maturity tests (we’ve done them for you!), discuss what happens when you dry and sieve HOTBIN compost (don’t worry no-one is suggesting you need to do this) and finally do a bit of mud pie play to demonstrate a property called ‘colloidal behaviour’’. Finally we will tie these properties back to humeric substances and suggest that what you really need to look for in fabulous compost is high humeric substance content.

This blog is a little more scientific in nature than some of our others – so if you want the headline without the science it is this:

What a compost looks like can be deceptive. HOTBIN compost is often very sticky and very moist/wet and looks lumpy and perhaps even needing further composting. Tests show rather than it being ‘poorly’ composted, quite the reverse – it appears to have a very high humeric substance content and this is good news for your soil and plants – humeric substance is known as ‘black gold’ for a reason!

If your compost looks like (Fig 4&5), or even (Fig 6) below it is OK to dig in to your soil and does not need ‘more composting’. If you only want ‘fine’ particles of compost e.g. looking like (Fig 1) or (Fig 2) – the solution is fairly simple – dry your compost and then sieve it – you will surprised by how much fine material there is in HOTBIN Compost.

Our analysis tour includes;

1. Visual inspection

2. Carbon / nitrogen maturity test

3. Visual after drying and sieving

4. Pliability / colloidal behaviour

5. Humus test

6. Result to quality – is it fabulous?

1. Visual inspection – Below are 6 samples of compost

(Fig1) Vermicompost

(Fig2) Garden centre compost laid out dry

(Fig 3) Typical cold compost

(Fig4) HotBin compost at 3 Months

(Fig5) HOTBIN compost that is it too wet

(Fig6) HOTBIN compost that has gone

anaerobicNow in our earlier blog (good, bad or fabulous compost) we outlined details on how different experts defined good compost. If we asked this group of experts to visually judge the samples above here is what we would expect:

(Fig1) Vermicompost – looks fine and rich, super

(Fig2) Garden centre compost laid out dry – looks very fine and free flowing, uniform and has probably been sieved

2. Carbon / nitrogen maturity test

Industrial producers of compost (i.e. compost sold in garden centres) do a check to establish how active the bacteria are. Above a certain level and the compost is too active (i.e. not mature & stable) it needs to be left longer otherwise it can draw nitrogen from the soil as bacteria continue to use the carbon in the remaining compost. The maturity and stability test can be undertaken via the Solvita compost test method. You can do these at home, although it gets expensive!

Garden centre compost (Fig2) would not have gone on sale without passing the C/N maturity and stability tests. How did HOTBIN (Fig4&5)compare? Well they both fall in the stable and mature range. This will surprise a lot of experts as they look lumpy and lumpy normally means large pieces of non-composted material which is highly likely to result in an ‘active’ rather than stable result.

3. Visual after drying and sieving

We recently tested a range of compost sieves (see guide to compost sieves post). We know wet and sticky compost is a complete pain to sieve. When testing the Compostsifter it failed to sieve any of HOTBIN (Fig5). So we dried the compost and tried again. This reminded us of an old saying – ‘looks can be deceptive’. Below is the result of the sieving test.

HOTBIN compost sieved

The result was about 80% of all the compost went through the fine (8mm mesh) sieve. There is about 15% of wood chip pieces (0.8-1.5mm), and 5% oversize non-composted items (notably pampus grass roots – these are possibly going to take the record for the hardest most difficult material to compost – but that’s another blog!). I’d just like to say this sieve result is not a one off – we have seen it many times, same results.

If we visually compare the sieved HOTBIN compost with the sieved garden centre compost they now look very similar. So was the problem just that the HOTBIN sample has been stuck in the base and got wet? Is the difference just about one compost being very wet and another compost being dry? No!

4. Pliability / colloidal behaviour

When we sieve and handle HOTBIN compost we notice something else – it is very sticky. It rolls into balls in the sieves, when you grab a handful you can make a ball. It is ‘pliable’ just like a potter’s clay or children’s plasticine.

HOTBIN Vs Garden Centre on compost pliability

There are two common substances in soils and composts that create a pliable mix – clay and humeric compounds. Both these are ‘colloidal’ materials and it is this property and the resultant way they hold water that leads to the pliability.

We can take the pliability test a little further. If we make a ball of moist compost from Garden centre compost and HOTBIN compost (Fig5) and leave then to dry in the sun for 4 days. Now what happens when we try and squeeze each ball?

HOTBIN Vs Garden Centre – compost pliability after drying

The garden centre compost sample behaves more like peat – it sticks when wet, dries fast (i.e. looses water 2-4 times faster) and then the organic material falls apart when the dry ball is pressed. Whilst the HOTBIN sample is still damp and pliable, it forms a very hard solid outer layer material with soft inner. Even after 100% drying and re-wetting the pliability returns.

At this stage we should mention that HOTBIN composting (and certainly the batch of HotBin compost above ) had no soil added – hence the pliability is not believed to be due to soil clay.

5 Humus test

We think (and we mean ‘think’ because we have no laboratory proof) that it is possible that HOTBIN compost has more humeric substances than many other composts.

HOTBIN compost – Pliable humus

Can we test for humeric substances? The answer is yes but not easily outside a fully operational soil testing lab. There is a relatively simple humus soil test – targeted at measuring the concentration of humeric substances in soils. The HOTBIN samples are off the scale – but a note of caution – the test aims to give a reliable field test for soils with 0.5-6% humeric substances. It cannot be relied on for concentrations well above this.

6 Result to quality – is it fabulous?

We believe there is a real difference between compost and compost that contains very high amounts of humeric substances. Partly decomposed material (compost) will continue to decompose when added to the soil and eventually the carbon cycle completes and it is returned to carbon dioxide and a small amount of recalcitrant humus in the soil. Humeric substances do not decompose in the soil (to any great extent) so adding a concentrated form will improve your soil faster.

HOTBIN compost – drying out

As a company we are not into making claims about our products we can’t substantiate – to be clear – we believe we can explain the appearance and behaviour of HOTBIN compost. We believe we can trace (but not prove it yet!) this back to higher humeric substance content in HOTBIN compost. One day we will have the evidence – until then we believe our logic and science has merit, you can do your own testing, contribute to the debate or ignore our findings as just marketing waffle!

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My name is Tony Callaghan and after getting frustrated with my overflowing compost bin and failing to find an alternative compost bin, I eventually concluded my best option was to design and manufacture a new ‘hot composting bin’ myself, I called it the HotBin.

If the HotBin blogs are useful please like us on facebook, tweet about it, forward to friends, family and colleagues who you know are interested in gardening and recycling food waste.

Liability: the opinions expressed, methods outlined, any ratings offered etc are personal opinions of the author. The advice and associated tools and information is supplied gratis as an aide. No guarantee is made and no liability whatsoever is accepted for the use.

hotbincomposting · A Hot composting BIN that lets you put more food & garden waste IN